Various studies have been conducted on decomposition devices for use to decompose, for example, nitrogen oxides (hereinafter, simply called NOx sometimes) such as nitrogen monoxide and nitrogen dioxide contained in automobile emissions and the like. For example, it was reported that use of an electrode containing solid electrolytes on which nanometer-sized noble metals are highly dispersed achieves high NOx cleaning efficiency (about 80%) (Patent Document 1); a study shows that an electrode reaction area is enlarged by electronic conductors highly dispersed on solid electrolytes that are ionic conductors (Patent Document 2). It was further reported that a configuration in which substances having mixed conductivity, namely, substances having both ionic conductivity and electronic conductivity are arranged on ionically-conductive solid electrolytes can achieve highly selective NOx decomposition (Patent Document 3).
Another report shows that adopting an La-based perovskite oxide as a NOx-decomposition material allows selective detection of NOx with high sensitivity even in the presence of oxygen (Patent Document 4).